Democrat Joe Sestak raised $312,000 during the first three months of the year, a slim haul as he attempts to unseat U.S. Sen. Pat Toomey, R-Pa.

With those contributions, Sestak had $1.7 million on hand at the end of March.

Toomey's latest fundraising report showed him with nearly $7.3 million after raising $2.1 million last quarter.

Sestak's campaign confirmed the retired Navy admiral's fundraising figures after they were reported Tuesday by the Philadelphia Inquirer. His campaign spokeswoman had declined to release the totals since last week's reporting deadline.

"We're where we want to be," Sestak spokeswoman Danielle Lynch said in an email Tuesday, nearly a week after the reporting deadline.

Next year's Senate election is expected to be an expensive campaign, with spending likely to surpass the combined $30 million that Toomey and Sestak spent in 2010. The Pennsylvania race is among a handful of contests that could help determine whether Republicans maintain control of the Senate after 2016, and outside groups already are tracking it closely.

MATT ROURKE, AP

Joe Sestak

Joe Sestak (MATT ROURKE, AP)

The financial challenge for Sestak grew steeper last week when Allentown Mayor Ed Pawlowski became the second Democrat to announce a Senate run. That means Sestak now must win a contested primary in order to earn a rematch against Toomey.

Pawlowski faced fundraising challenges during his short-lived gubernatorial contest last year. But his campaign consultant, Mike Fleck, says Pawlowski will be spending "most of his free time over the next several months" making fundraising calls.

The announcement, which came in a news release to media outlets, was launched in tandem with a social media campaign...

Calling Allentown a "shining example" for the rest of the state, Mayor Ed Pawlowski officially jumped into the race for U.S. Senate on Friday, ending several days of speculation.

The announcement, which came in a news release to media outlets, was launched in tandem with a social media campaign...

(Emily Opilo and Laura Olson)

Pawlowski's first Senate fundraising report will be due in July.

The Democratic field could grow wider in the coming weeks. Montgomery County Commissioner Josh Shapiro has been courted by national Democrats who want him to join the race. Former U.S. Rep. Chris Carney of Susquehanna County also has said he's considering a Senate bid.

Responding to Sestak's fundraising figures, Toomey's campaign emphasized the support that the freshman senator has received from Democrats. Comcast executive David L. Cohen, a former top adviser to Ed Rendell, has hosted two events for the campaign, and Cynthia Shapira, who raised money for Barack Obama, is listed on Toomey's recent fundraising report.

Toomey campaign manager Peter Towey said the contributions from Democrats show "a bipartisan embrace of Pat's candidacy and an appreciation for his body of work in the Senate."

Toomey's latest report, which was posted on the Federal Election Commission website Tuesday, also showed financial support from a number of high-profile Republicans.